In about year 93 of the common era, historian Flavius Josephus set out to write the history of the Jews.

Toward the end of his 20-volume “Antiquities,” he mentions a Jewish high priest named Ananus who capriciously condemns a man to death by stoning. That man was “James, the brother of Jesus,” Josephus writes, “the one they call messiah.”

Oh, him.

Such is the challenge to any historian who tries to examine the life of Jesus from a scholarly perspective. Josephus’ offhand remark is one of the only mentions of Jesus in contemporary writings. He lives in the gospels, but hardly anywhere else. If you want to know more about Jesus the man, you must search for him between the verses of the believers.

Reza Aslan, a religious scholar and author of the bestselling Islamic study “No god but God,” attempts this distillation in a new biography, “Zealot,” filtering out what he considers the biases of gospel writers based on the political realities the era.

Aslan writes that Jesus’ life after death is what’s most important to his understanding — religiously and literally. His purported resurrection is, of course, a central belief of Christianity. But the destruction of Jerusalem by the Romans, coming during the time of the religion’s infancy, also shapes how Christians today view Jesus’ life and his teachings.

“Greek-speaking Jews . . . steadily transformed Jesus from a revolutionary zealot to a Romanized demigod,” Aslan writes. “From a man who tried and failed to free the Jews from Roman oppression to a celestial being wholly uninterested in any earthly matter.”

A LIFE OF SYMBOLISM

From the beginning, the New Testament is embellished for the sake of prophecy and tradition, Aslan argues.

Jesus’ birthplace was placed in Bethlehem rather than his parents’ hometown of Nazareth, for instance, to link Jesus to the past kings of Israel. As the Gospel of Luke says of his father, “Joseph belonged to the house and lineage of David.”

Luke explains the move as being required by a Roman census. But what kind of census forces everyone to pack up and visit their place of birth, waiting there for months until counted, while the economy of an empire is put on hold?

Luke knew the Bethlehem journey was fiction — and so did his early readers.

“The infancy narratives in the gospels are not historical accounts, nor were they meant to be read as such,” Aslan writes. “They are theological affirmations of Jesus’ status as the anointed of God. The descendant of King David. The promised messiah.”

The New Testament is as much an argument for the holiness of Jesus as it is a telling of his life. Tales get massaged, even from gospel to gospel, to address any questioning of the faith.

What to do about John the Baptist, for example? John’s acts and martyrdom were legendary, so much so that he had many devotees after death before they were subsumed by Christianity. To some, John would seem to be the superior figure — the one who baptized Jesus.

After Jesus’ death in roughly 30 CE, his story and teachings are passed down by oral tradition and letters. Eventually, in about 70 CE, scholars believe the first gospel, that of Mark, is written.

In Mark, Jesus is baptized, but John says that “there is one coming after me who is stronger than I.” Strangely, however, John does not recognize Jesus as that messiah, Aslan writes.

Between 90 and 100 CE, the next two gospels, Matthew and Luke, are written. This time, in Matthew, John does recognize Jesus and only agrees to baptize him when Jesus insists.

It’s in the last gospel, John, written sometime between 100 and 120 CE, that John the Baptist is completely minimized. He does not baptize Jesus. He merely witnessed him baptized by the Holy Spirit, then commands his disciples to follow Jesus instead.

A TIME OF PROPHETS

John the Baptist wasn’t the only prophet with whom early followers of Jesus had to contend. With Jerusalem occupied by the Romans, apocalyptic beliefs were quite common. People wandered in from the wilderness every day declaring themselves the messiah.

Aslan runs down just a few: the Egyptian, who gathered his followers on the Mount of Olives and said he could cause the walls of Jerusalem to crumble at his command; Theudas the Wonder Worker, an “enchanter” who said he would divide the River Jordan; and Hezekiah the Bandit Chief, who robbed the countryside while preaching against Herod.

A few years after Jesus’ death, in 36 CE, a man named “The Samaritan” climbed Mount Gerizim and told his followers he would reveal “sacred vessels” hidden there by Moses. Pontius Pilate had him killed, just as all other would-be prophets.

To the Romans, Jesus was no different. Arriving in Jerusalem with his disciples, preaching of the coming Kingdom of God, throwing the money changers out of the Temple, these are the actions of an insurrectionist. Which is why Jesus is crucified with the title “King of the Jews,” a reflection of the crime of treason.

The Romans weren’t wrong, Aslan argues. “The central theme and unifying message of Jesus’ brief three-year ministry was the promise of a Kingdom of God,” he writes. And this kingdom was neither in the distant future, nor some celestial plane. Aslan writes that the only passage that suggests so is John 18:36, “My kingdom is not of this world,” which he not only discounts as propaganda, but also says could be mistranslated from the Greek. A more accurate rendering would be “not part of this order/system [of government].”

Jesus was calling for a Kingdom of God on Earth, one not under the rule of Rome or the corrupt priests. “Simply put, the Kingdom of God is a call to revolution.”

The revolution is not a peaceful one, either. “Think not that I am come to send peace on earth. I came not to send peace, but a sword,” says Matthew 10:34.

“What I argue is that all of Jesus’ words and actions must be understood both within the political context of his time and within the religious context of Judaism,” Aslan tells The Post. “What the writers of the gospels did was to cleanse statements such as ‘love your enemies’ and ‘turn the other cheek’ of their Jewish context and transform them instead into abstract ethical principles.

“But such statements are grounded in Jesus’ beliefs as a Jew and as a follower of the Torah,” Aslan says. “As a Jew, Jesus would have understood these commandments to apply only to relations among Jews, not between Jews and gentiles. Recall that the oft-repeated commandment to ‘love your neighbor as yourself,’ was originally given strictly in the context of internal relations within Israel. The verse in question reads: ‘You shall not take vengeance or bear a grudge against any of your people, but you shall love your neighbor as yourself’ (Leviticus 19:18). To the Israelites, as well as to Jesus’ community in 1st century Palestine, ‘neighbor’ exclusively meant one’s fellow Jews.”

SPREADING THE WORD

So, if Jesus was just another prophet in a land thick with them, how does his ministry endure?

First, of course, was the appeal of Jesus himself. Even if you believe only the most basic outlines of the New Testament, here was a man who recruited devoted apostles and large crowds for his teachings. Aslan notes that Jesus would have had the same rural accent as those he was preaching to, that his message that the “meek shall inherit the earth” over foreign occupiers and an out-of-touch ruling class resonated greatly with the poor and oppressed.

But what truly sets Jesus apart from the other prophets of his day is the story of his resurrection.

Aslan does not argue the factuality of Jesus’ return from the dead. To believe it is to have faith; it is not something that can be debated as a historical event.

Yet even as a parable, his return neatly sidesteps the messiah problem. Had Jesus simply died, Jerusalem still under Roman rule, his ministry would have failed, his prophecies unfulfilled. His resurrection — and promised appearance in the final days — gives fresh hope. There was nothing like it in Jewish tradition.

However, in the years after the crucifixion, there was a split among his followers. The apostles, led by James, Jesus’ brother, stayed in Jerusalem, awaiting his return. They were illiterate, Aramaic-speaking, still identifying as Jews and believing that most converts to Jesus’ teachings should come from among the Jews.

The Hellenic branch, meanwhile, made up of Jews living abroad, were primarily Greek speaking and less bound to Jewish tradition. The most influential of these was Paul, whose vision on the road to Damascus transformed him from Saul the unbeliever.

Paul says he is visited by Jesus after his resurrection and is provided with new teachings. His letters are passed around the gentile communities in the decades following Jesus’ death, and the Gospel of Luke is believed to have been written by one of his disciples.

Where James wants his followers to adhere to the Jewish Laws of Moses, Paul begins to drift from them. He speaks out against circumcision and says in Romans: “Christ is the end of the Torah.”

Jesus and James were not interested in creating a new religion, Aslan writes, but that’s exactly what Paul and the gospels helped create.

EMBRACING ROME

Finally, there is the political upheaval in the years following Jesus’ death, which may have the greatest impact on Christianity.

In about 70 CE, Jerusalem briefly breaks free of the empire, as a group of Jewish rebels called the sicarii, or daggermen, take the city. Rome reacts viciously. Jerusalem is razed, its name to be “forgotten to history” the emperor orders. The Temple is destroyed, and the Jews are scattered.

That same year, the first gospel, Mark, is written. Against that backdrop, would not Jesus’ role as a Jewish rebel be downplayed in favor of someone who preached that salvation awaits us all, even Romans?

Take the story of Pilate. In all the contemporary histories, he is a cruel Roman governor, slaughtering Jews without a thought. Yet in Mark’s telling, he not only calls Jesus before him for a trial, he tries to spare him.

“Why would Mark have concocted such a patently fictitious scene?” Aslan asks. “The answer is simple: Mark was not writing for a Jewish audience. Mark’s audience was in Rome.”

Those changes, and Paul’s influence, led to “a wholly new religion free from the authority of a Temple that no longer existed, unburdened by a law that no longer mattered and divorced from a Judaism that had become pariah was enthusiastically embraced by converts throughout the Roman Empire.”

It also falsely shifted the blame for Jesus’ death to the Jews, leading to centuries of anti-Semitism. By the Gospel Matthew, Pilate literally washes his hands of the matter, absolving Rome of his death. And the crowd of Jews cries out “His blood be on us and all our children” (Matthew 27: 25), an oath sadly come true.

AN INCOMPLETE PICTURE

“Everything Jesus said or did must be vetted by the incontrovertible fact that he was an uneducated, illiterate Jewish peasant who was executed as a state criminal for the crime of sedition,” Aslan says. “Once you start with that fact, then which of his statements and/or actions are more likely and which are less likely becomes easier to reveal.”

Not that such debates matter much. For his followers, the matter of Jesus’ life and teachings comes down to one word: belief.

“Among all the other failed messiahs who came before and after him, Jesus alone is still called messiah,” Aslan writes. “It was precisely the fervor with which the first followers of Jesus believed in his resurrection that transformed this tiny Jewish sect into the largest religion in the world.”